Glutamine synthetase, which catalyses the incorporation of ammonium into glutamate, is a key enzyme of nitrogen metabolism found in all domains of life. Several types have been described, differing in their oligomeric structures and cofactor requirements.
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SYSTEMATIC NAME
IUBMB Comments
L-glutamate:ammonia ligase (ADP-forming)
Glutamine synthetase, which catalyses the incorporation of ammonium into glutamate, is a key enzyme of nitrogen metabolism found in all domains of life. Several types have been described, differing in their oligomeric structures and cofactor requirements.
senescence-specific downregulation of plastidic glutamine synthetase, this is retarded by fertilisation of plants with nitrate or ammonium, but not urea, at the onset of leaf senescence, overview
senescence-specific downregulation of plastidic glutamine synthetase, this is retarded by fertilisation of plants with nitrate or ammonium, but not urea, at the onset of leaf senescence, overview
expression of GFP driven by the Gln-1;2 promoter occurs in both developed and developing new leaves of plants in the vegetative growth stage. Bright GFP signals are detected in mesophyll cells within the margins of developed leaves. Fluorescence is also recorded in the cells of vascular bundles along the veins in developed leaves. In the developing new leaves, fluorescence is weak and signals are confined to the trichomes
two GS isoforms are encoded in the genome of higher plants: the cytosolic Gln synthetase isoform (GS1) and the chloroplastic Gln synthetase isoform (GS2). GS2 is encoded by a single gene (Gln-2), whereas GS1 is encoded by a multigene family, suggesting a complex role of GS1 with respect to plant N assimilation
two GS isoforms are encoded in the genome of higher plants: the cytosolic Gln synthetase isoform (GS1) and the chloroplastic Gln synthetase isoform (GS2). GS2 is encoded by a single gene (Gln-2), whereas GS1 is encoded by a multigene family, suggesting a complex role of GS1 with respect to plant N assimilation
enzyme mutants, single mutant gln1-2 and gln1-1:gln1-2 double mutant, show impairment of seed germination and seedling establishment. The negative effect of Gln1-2 deficiency, causing slower seedling development in the mutants, is associated with reduced N remobilization from the cotyledons and can be fully alleviated by exogenous N supply. Phenotypes, overview
Gln synthetase catalyzes the assimilation of ammonium into Gln and constitutes as such a central component of the N assimilatory pathway in plants. In shoots, both GS1 and GS2 contribute to ammonium assimilation into Gln
specific roles of the individual GS1 isogenes with respect to nitrogen remobilization, early seedling vigour, and final seed productivity. Isozymes Gln1-1 and Gln1-2 play specific roles in seed germination and seedling establishment in Arabidopsis thaliana
Gln synthetase catalyzes the assimilation of ammonium into Gln and constitutes as such a central component of the N assimilatory pathway in plants. GS2 is the predominant GS isoform in leaves of vegetatively growing plants. In shoots, both GS1 and GS2 contribute to ammonium assimilation into Gln
Gln synthetase catalyzes the assimilation of ammonium into Gln and constitutes as such a central component of the N assimilatory pathway in plants. In shoots, both GS1 and GS2 contribute to ammonium assimilation into Gln
Gln synthetase catalyzes the assimilation of ammonium into Gln and constitutes as such a central component of the N assimilatory pathway in plants. In shoots, both GS1 and GS2 contribute to ammonium assimilation into Gln. Isozyme Gln-1;2 is essential for ammonium assimilation and amino acid synthesis. Gln-1;2 is the main isozyme contributing to shoot GS1 activity in vegetative growth stages and can be up-regulated to relieve ammonium toxicity
specific roles of the individual GS1 isogenes with respect to nitrogen remobilization, early seedling vigour, and final seed productivity. Isozyme Gln1-2 plays an important role in N remobilization for both seedling establishment and seed production in Arabidopsis thaliana
the phenotype of the single mutant gln1;1 is similar to the wild-type, while the double mutant gln1;1:gln1;2 shows a growth that is significantly impaired irrespective of N regime
the phenotype of the single mutant gln1;1 is similar to the wild-type, while the double mutant gln1;1:gln1;2 shows a growth that is significantly impaired irrespective of N regime
the phenotype of the single mutant gln1;1 is similar to the wild-type, while the double mutant gln1;1:gln1;2 shows a growth that is significantly impaired irrespective of N regime
the phenotype of the single mutant gln1;2 and double mutant gln1;1:gln1;2 shows a growth that is significantly impaired irrespective of N regime. The GS1 enzyme activity is significantly reduced in both gln1;2 and gln1;1:gln1;2. Along with this, the ammonium content increases while that of Gln decreases
the phenotype of the single mutant gln1;2 and double mutant gln1;1:gln1;2 shows a growth that is significantly impaired irrespective of N regime. The GS1 enzyme activity is significantly reduced in both gln1;2 and gln1;1:gln1;2. Along with this, the ammonium content increases while that of Gln decreases
the phenotype of the single mutant gln1;2 and double mutant gln1;1:gln1;2 shows a growth that is significantly impaired irrespective of N regime. The GS1 enzyme activity is significantly reduced in both gln1;2 and gln1;1:gln1;2. Along with this, the ammonium content increases while that of Gln decreases
stably transgenic Arabidopsis thaliana ecotype Columbia plants expressing a p35S::GLN2::green fluorescent protein chimeric reporter were constructed. A 41-kD chimeric GLN2::GFP protein is present in both leaf mitochondria and chloroplasts of these stably transgenic plants
Gln2 isozyme expression is induced at high ammonium condition. The expression of GS2 isozyme is reduced in a double mutant gln1;1:gln1;2, especially under high ammonium condition
high ammonium treatment enhances the expression of the GS1 isogene Gln-1;2 encoding a low-affinity high-capacity GS1 protein in Arabidopsis thaliana shoots
the expression of Gln-1;3 does not respond to ammonium treatment and is only poorly affected by mutation of isogene gln1;2 and double mutation gln1;1-gln1;2
Supply of nitrogen can reverse senescence processes and affect expression of genes coding for plastidic glutamine synthetase and lysine-ketoglutarate reductase/saccharopine dehydrogenase